Mrs Grote claimed to have first suggested the History of Greece in 1823; but the book was already in preparation in 1822. In April 1826 Grote published in the Westminster Review a criticism of William Mitford's History of Greece, which shows that his ideas were already in order. From 1826 to 1830 he was hard at work with John Stuart Mill and Henry Brougham in the organization of University College London. He was a member of the council which organized the faculties and the curriculum. In 1830, owing to a difference with Mill as to an appointment to one of the philosophical chairs (Grote objected to John Hoppus), he resigned his position. He rejoined the council in 1849 and was appointed Treasurer in 1860, then President in 1868. In his will Grote left ₤6000 as an endowment for the Chair of Philosophy of Mind and Logic at University College London.[5]

He went abroad in 1830, and spent some months in Paris with the Liberal leaders. Recalled by his father's death (6 July), he became manager of the bank, and took a leading position among the City Radicals.[6] In 1831 he published his important Essentials of Parliamentary Reform (an elaboration of his previous "Statement"), and, after refusing to stand as parliamentary candidate for the City of London in 1831, changed his mind and was elected head of the poll, with three other Liberals, in December 1832. After serving in three parliaments, he resigned in 1841, by which time his party ("the Philosophical Radicals") had dwindled away.

Portrait of George Grote, by Maull & Fox.

During these years of active public life, his interest in Greek history and philosophy had increased, and after a trip to Italy in 1842, he severed his connection with the bank and devoted himself to literature. In 1846 the first two volumes of the History appeared, and the remaining ten between 1847 and the spring of 1856. In 1845, with William Molesworth and Raikes Currie, he gave money to Auguste Comte, then in financial difficulties. The formation of the Sonderbund (20 July 1847) led him to visit Switzerland and study for himself a condition of things in some sense analogous to that of the ancient Greek states. This visit resulted in the publication in The Spectator of seven weekly letters, collected in book form at the end of 1847 (see a letter to de Tocqueville in Mrs Grote's reprint of the Seven Letters, 1876).

In 1856, Grote began to prepare his works on Plato and Aristotle. Plato and the Other Companions of Sokrates (3 vols.) appeared in 1865. That work made him known by some as "the greatest nineteenth-century Plato scholar."[7] The work on Aristotle he did not complete. He had finished the Organon and was about to deal with the metaphysical and physical treatises when he died at his home in Mayfair, London, and was buried in Westminster Abbey. The house, No. 12 Savile Row, now has a commemorative brown plaque on it.[8]

He is said, in some estimations, to have been a man of strong character and self-control, unfailing courtesy and unswerving devotion to what he considered the best interests of the nation. Other historians, such as Guy MacLean Rogers, consider he can reasonably be accused of anti-clerical bias. Grote's time on the Council at University College, London was characterised by his contentious approach to two liberal nonconformists: John Hoppus and James Martineau, both of whom found ways to work around his opposition. Grote's life has attracted a wide variety of biographical comment due to his strong views.[9]

^Charles Darwin remembered that he was pleased by the simplicity and absence of all pretension in Grote's manners. See Barlow, Nora ed. (1958). The Autobiography of Charles Darwin 1809-1882. London: Collins, p. 111.